Process of producing anthranilic acid.



' reel; amount of hydrochloric acid Mama-a!- RALPH S. PQTTER, U5GRANTWOOID, NEW JERSEY, ASSIGNGhfi TO THE BARRETT oFFZlTCE.

GUMIAN'Y, A CQRPOEATIOII OF NEW JERSEY. Y

FRODUCIHG ANTHRANILKC AGED.

1N0 Drawing.

all whom it may concern:

- Be it known that I, RALPH S Powell, a citizen of the United States,residing at Grantwood, in the county of Bergen and State of New Jersey,have invented certain new and useful Improvements in Processes ofProducing Anthranilic Acid of which the following is a specification.

This invention relates to process of producing enthranilic acid and hasfor its oh ject to produce the acid in such :1 manner that a minimumloss of this valuable mo terial results, while, at the some time,cheepening the cost and regaining valuable b3 According to the ordinarymanufactun ing practice the raw materials used are in the lipproxim'ateproportion of their inolecular weights, that, is, about 147 parts ofphthalimid to M parts of sodium hypochlorite to 120 parts of sodiumhydroxid. A solution of sodium hvpochlorite is added to a mixture ofsodium hydroxid and phthulimid in the )roportions indicated and afterthe reaction ms been completed there is left in the reaction mixture thesodium saltof unthranilic acid, sodium carbonate and sodium chlord. Allthese materials are in solution, and when i'c is attempted seem.

woo3 one;

Since anthranilic acid is quite insoluble it would he precipitated inpractically quantitative amounts hr addingl'hc exa tly cor- :of some ofthe shthraniiic acid, which is either left. in solution as the sodiumsalt due to the use of insufficient hydrochloric or sul-- "furic acid oris dissolved as she hydrochlcrid or sol. sis due to the use of too muchhydrochloric or sulfuric acid. The reason -it; is diiiicult to addexactly she right amount specification of Letters l-atent.

or sin er-1c ecid is chm vsrzllaixscn'ted Nov. Cl 8,1918% Applicationfiled June 1?. was. Serial No. 3624,83 2.

product-S of the process. lhis inventioniiis ordinarily made by treatingphthalhnhl with sodium hypochlorite and sodiuni hydroxid in accordancewith the it'ollowing equation. v v,

v COONo 64 :q}I2 M2603 NsCl mo ,to .precipitzitc the antln'zinilic :ioidby the addition of hydrochloric or sulfuric ucid difiiculty isexperienced in determining the i correct amount of the mincrul n'cid tohe added because if insuliicicnshydrochloric for sulfuric acid is addedsome ofthek n; thrunilicucid will not he precipitated, and

iitoo much is added some of the mum-l1- nilic acid will be dissolved inthe exccss'ecid. F or example, if three molecular weights of Hill to onemolecu'l'ir weight of the sodium salt of anthrani c scidfis uscll 'hofollowing reaction will take place. (the Nei l takes no part inthereactioiijh of Hm is added the h vdrochloric tliranilic acid, whichis fairly sol water, will he formed in accordance I this equation,

SNnCl co mo un nci t at,

valueless product such as sodium chlorid or sulfate as representedbyequation (2).

I have therefore found the following cycle of operations to be workable,and that when so carried out, anthranilic acid may be produced in a moreeconomical manner than heretofore done.

I prefer to treat'the products of reaction ('1) with carbon dioxid,thereby converting the sodium carbonate into bicarbonate which isrelatively insoluble due to the presence of other soluble sodium ionswhereby it may be filtered oil and regained. By this method at least 50%of the sodium present H The S0 is only slightly soluble in water and itis too weak an acid .to form a sulfite salt with anthranilic acid.Therefore, after the reaction mixture, resulting from the treatmentindicated in equation (1), has been treated with carbon dioxid andfiltered,

the filtrate may with impunity be treated with sufiicient SO to assurethe precipitation of all 'of-the anthranilic acid because the-re is nodanger of using somuch SO, that some anthranilic acid will be lost.

It is thus clear that the use of SO for precipitating anthranilic acidpossesses the following advantages over the use of hydrochloric orsulfuric acid: Higher yields may be obtained; there is no danger efadding an excess; by passing in the S0 until there is a distinct odor ofSO from the reaction mixture a sufficient amount is assured; less careis required to add the proper amount of acid; and an iron reactionvessel and an described in connection with the separation of anthranilicacid from the reaction mixture resulting from the treatment of phthali-'mid with sodium hypochlorite and sodium hydroxid, it is obvious that itis applicable to the reaction mixture produced when potassium is usedinstead of sodium and hypobromite 1s used instead of hypochlorite, andthe claims are intended to.cover this.

Having now described my invention what nilic acid.

COOH

Nanso, NH,

I claim and desire to protect by Letters Patl. The herein describedprocess which comprises passing carbon dioxid into a so-' lutioncontaining an alkali salt of anthranilic acid and an alkali carbonate,to convert mostof the carbonate into bicarbonate, filtering off theprecipitated bicarbonate and passing an excess of sulfur dioxid into thefiltrate,

' 2.v The herein described process which comprises passing carbon dioxidinto a solution containing an alkali. salt of anthranilic acid and analkali carbonate, to convert most of the carbonate into bicarbonate,filtering off the precipitated bicarbonate and passing sulfur dioxidinto the filtrate in suflicient amount to preci itate substantially allof the anthranilicaci 3. The 'herein described. process which comprisespassing carbon dioxid into a solution containing the sodium salt ofanthra nilic acid and sodium carbonate, to convertmost of the sodiumcarbonate into sodium bicarbonate, filtering off the precipitated.sodium bicarbonate and passing an excess of sulfur dioxid intothefiltrate.

4. The herein described process which comprises passing carbon dioxidinto a solution-containing the sodium salt ofanthranilic acid and sodiumcarbonate, to convert inost of the sodium carbonate into sodiumbicarbonate, filtering ofl? the precipitated sodium bicarbonate andpassing sulfur dioxid into the filtrate in suflicient amount toprecipitate substantially all of the anthla In testimony whereof I aflixmy signature.

RALPH s. POTTER.

